Polarization study of a boosted W boson decaying hadronically at the LHC with jet substructures and a multivariate analysis

Atri Dey; Tousik Samui

doi:10.1140/epjc/s10052-023-12118-1

2024 Impact factor 4.8

Particles and Fields

Open Access

Eur. Phys. J. C (2023) 83: 1002
https://doi.org/10.1140/epjc/s10052-023-12118-1

Regular Article - Theoretical Physics

Polarization study of a boosted W boson decaying hadronically at the LHC with jet substructures and a multivariate analysis

Atri Dey¹^,2 and Tousik Samui²^,3^b

¹ School of Theoretical Physics, Dublin Institute for Advanced Studies, 10 Burlington Road, Dublin 4, Ireland
² Regional Centre for Accelerator-Based Particle Physics, Harish-Chandra Research Institute, A CI of Homi Bhabha National Institute, Chhatnag Road, Jhunsi, 211 019, Prayagraj (Allahabad), India
³ Department of Physical Sciences, Indian Institute of Science Education and Research Kolkata, 741 246, Mohanpur, India

^b tousiksamui@gmail.com

Received: 20 May 2023
Accepted: 9 October 2023
Published online: 6 November 2023

Abstract

The study of the polarization of heavy particles is an important branch of research in today’s collider physics. The massive W boson has two types of polarization states, which usually are studied via the angular distribution of its decay products. We present a jet substructure-based study on the polarization of a boosted W boson decaying hadronically, which forms a fat jet, in pp collision at the $\sqrt{s}$ $\sqrt{s}$ = 14 TeV at the LHC. Two different methods, viz.N-subjettiness and Soft Drop, were used to find the subjets, which are approximately considered to be the two hadronic decay products of W, inside boosted W jets. These subjets were then used to calculate two variables $p_{θ} = | E_{1} - E_{2} | / p_{T}^{W}$ $p_\theta =|E_1-E_2|/p_T^W$ and $z_{j} = max (p_{T_{1}}, p_{T_{2}}) / p_{T}^{W}$ $z_j=\max (p_{T_1},p_{T_2})/p_T^W$ , where the subscripts 1 and 2 are for two subjets and W represents the reconstructed W jet. We then prepared the templates for longitudinally and transversely polarized W. These templates were used to extract the fractions of different W polarization in a mixed sample with relatively good accuracy.

© The Author(s) 2023

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